This invention relates to improved means for orienting to a horizontal plane, the gimbal system supporting the lubber lines and compass card immersed in damping fluid of a magnetic compass of the type enclosed in a spherical housing.
In my U.S. Pat. No. 3,949,483, which is incorporated by reference herein, is shown and described compasses of the spherical type with a double axis internal gimbal system which is uniquely capable of being manually adjustable to position it in a horizontal plane to correct for any angle of a compass mounting surface between horizontal and vertical. This feature has proven valuable, since it makes it possible to mount the compass on any surface from horizontal to vertical.
However, difficulties have been encountered during installation due to the uniqueness of the design and the installer's resultant inability to operate the adjusting mechanism or his ignorance of it. Because of my continuing interest in the performance of these compasses, which are currently produced in substantial quantity, I have observed many installations on many different vessels. Of these installations, a significant number have been made without adjusting the gimble support unit to permit the gimbal system to assume a level attitude. This, of course, detracts markedly from the stability of the gimbal system and its associated forward reference, the lubber line. In some observed cases of vertical mounting, the lubber line was free to rotate in either direction and through 360.degree., making the compass useless.